Environmental Fate and Transport Modeling
Knowing the potential for a chemical to be released from a product, or into a workplace or environmental setting, is a key component of the risk assessment process. Cardno ChemRisk engineers employ a variety of state-of- the-art- tools to evaluate or predict the movement of chemicals in environmental and occupational settings, as well as biological systems. These include screening models such as ECETOC-TRA, E-Fast and SCREEN 3 which give a general sense of the potential for chemical release, and higher tier models such as EUSES, ConsEXPO and AERMOD, which provide a more precise understanding.
Physiologically-Based Pharmacokinetic Modeling
Understanding the disposition of a chemical once it enters the body is often critical in evaluating the potential human health risks associated with exposure to that chemical. Cardno ChemRisk scientists can utilize Physiologically-Based Pharmacokinetic (PBPK) models to assess the biological fate and transport of chemicals to target tissues. These models allow Cardno ChemRisk scientists to evaluate a wide variety of conditions associated with chemical and product life cycles, and to understand where risk management measures may be most effective.
Because environmental data sets can be large and complex, various advanced statistical analysis methods are often needed to be able to unlock the information within the data sets. Cardno ChemRisk scientists have experience with a number of statistical tools – such as geostatistics, time series analysis, multiple comparison tests, analysis of variance, mixed linear models, and multiple regression analysis – that can be used to fully understand environmental data sets. These methods are used to answer questions regarding the nature and extent of chemical contamination, understand how exposures change temporally and spatially, and characterize the relationships between concentration and ecotoxicity test results.
At environmental sites that have been contaminated by multiple sources or industrial processes, it is necessary to be able to characterize the contributions of each source to the overall contamination of a site. Cardno ChemRisk scientists employ state-of-the-art methods for chemical fingerprinting such as principal components analysis (PCA), polytopic vector analysis (PVA), positive matrix factorization (PMF) and discriminant analysis to identify and characterize the contributions of different sources of contamination at a contaminated site.
The relationship between the dose of a chemical and the incidence of an adverse health effect needs to be understood to characterize the human health risk posed by exposure to a chemical. Cardno ChemRisk scientists understand how to apply current methods for dose-response modeling to estimate unit risks and reference doses for chemicals based on data from either animal toxicity tests or human epidemiological studies. Cardno ChemRisk scientists have applied these methods to chemicals such as benzene, hexavalent chromium, and tetrachloro-p-dioxin as well as other constituents such as tire wear particles.
A broad range of exposure scenarios need to be assessed to understand the chemical risks associated with a product – including industrial, professional and consumer uses. Cardno ChemRisk scientists have a history of developing comprehensive exposure scenarios that address the full range of media (air, water, soil and sediment), target groups (vulnerable sub-populations including children and pregnant women, consumers and workers) and routes of exposure (oral, inhalation and dermal). We have published more than 500 papers describing methodologies for using models, empirical data, simulation studies or surveys to characterize exposures attributable to the workplace, indoor and outdoor ambient environment, industrial materials and other consumer products.
Results of epidemiology studies are often the basis for concluding that a chemical causes certain health effects in exposed populations. Epidemiologists at Cardno ChemRisk have designed, conducted and interpreted the results of dozens of epidemiology studies to understand the foundation of hazard assessments for numerous chemicals, and have explained the strengths and limitations of the data to clients. For example, biomonitoring of the general population, including children, has become a popular method for identifying groups of people exposed to chemicals and at a theoretical increased health risk. Cardno ChemRisk evaluates such data to determine potential sources of exposure and to assist clients in understanding whether the detection of a particular chemical in the body of person is a valid and true indicator of increased health risk.